Menthol is commonly used as an analgesic and anesthetic agent in early treatment of sore throats and its vapors are known to have decongestant action as well as possessing antitussive properties.
Products for the foregoing purposes containing menthol have been well known for many years. Unfortunately menthol, above 0.1% by weight, acts as an irritant to the mucous membranes and, notwithstanding the desirability of utilizing higher concentrations for its physiological effect, achievement of concentrations above the 0.1% level has heretofore not been possible because of such concentrations could not be tolerated because of the "burning" sensation caused thereby. Such concentrations of 0.1% while sufficient to provide flavor and aromatic effect are insufficient to have any substantial decongestant action.
In studies published by an FDA advisory review panel, concentrations of 0.25 to 1% in aqueous solution have been recommended in the treatment of hemmorrhoids, a condition affecting rectal mucous tissue. Thus, it is clear from these studies that concentrations of menthol of the order of 0.25 to 1% are considered physiologically safe provided that the sensations caused thereby can be tolerated by the patient. These concentrations represent an increase of concentration of between 2.5 and 10-fold that which was heretofore available.
In studies relating to the provision of noncarieogenic sweetners utilizable in oral medicinal products, it has been found that that hydrogenated glucose syrup may be utilized in place of more traditional sweeteners. A substantial number of such syrups are available, suitably they are prepared by enzymatic hydrolysis of food starch followed by hydrogenation of the keto groups of the constituent sugars to the corresponding alcohol. The actual reduced sugar composition of these syrups will vary depending upon their origin, however, their common characteristic is that they are substantially devoid of oxo groups and contains a high proportion, suitably at least 75% of maltilol.